Project Number: 6225-32000-005-06
Project Type: Specific Cooperative Agreement

Start Date: Sep 30, 2010
End Date: Oct 01, 2012

Objective:
Evaluate a mobile nursery system for initial culture of sunshine bass fry including determination of appropriate size-fractions of natural zooplankton over time. Produce and determine survival and growth of triploid sunshine triped bass. Estimate costs and evaluate farm-level effects of the new mobile nursery system and triploid production of hybrid striped bass. Determine the effects of dietary lipid source and dairy/yeast prebiotic on growth performance, body composition, immune responses, and critical maximum temperature of channel catfish and sunshine bass. Clarify under what conditions qPCR is likely to produce anomalous results when used for fish pathogen detection. Identify the natural food cycle in Arkansas sunshine bass ponds during spring and early summer following fertilization with rice bran. Develop a cropping system to remove predacious copepods from sunshine bass fry pond water. Determine water temperatures and time of exposure necessary to induce a ‘heat hardening’ response in hybrid striped bass and channel catfish and determine the time course of protection associated with any ‘heat hardening’ response. Develop mechanistic and quantitative models to link aeration, DO concentration, and fish production in commercial catfish ponds with varying levels of aeration.

Approach:
A study will compare production parameters (survival, yield, etc.) of sunshine bass fry stocked directly into ponds to those of fry cultured for an initial period within the mobile nursery, then stocked into ponds. Shortly after the fertilization of eggs, the eggs will be subjected to a pressure shock. Triploid sunshine bass will be produced and stocked into ponds and survival and growth determined. Standard cost analysis techniques will be used to develop estimates of annual costs for models of the mobile nursery system and of triploid hybrid striped bass production. Species-appropriate basal practical diets for hybrid striped bass (42% protein, 12% lipid) and channel catfish (32% protein, 4% lipid) that will meet or exceed the known nutrient requirements of each species will be formulated with menhaden fish oil or flaxseed oil and 0 or 2% dairy/yeast prebiotic and tested in tank growth studies. Fish and environmental samples will be exposed to inactivated fish pathogens and qPCR will be used to determine what pathogen dose is required for detection. Sunshine bass fry ponds will be filled early spring and fertilized with rice bran at the rate of 100 lb/acre the first week and 50 lbs/acre the second and third weeks to determine succession of natural food items. Studies will be conducted with both hybrid striped bass and channel catfish to define and compare the critical maximum temperatures, develop protocols to induce a ‘heat hardening’ response, and characterize cross-protective benefits associated with this response. A dataset of commercial pond data will be used to develop: 1) a model of oxygen dynamics in commercial catfish ponds with varying levels of aeration; and 2) a response function of yield of catfish to aeration level. This response function will be evaluated to identify the biologically optimum level of aeration.